As vehicles improve in fuel economy, fuel cell vehicles and hybrid vehicles have been of great interest. The hybrid vehicle includes as its component a gasoline engine, a transmission, an inverter, a battery, and a motor as well as their controllers. Such vehicles require a motor that is highly reliable, efficient, variable in rpm and superior in control.
Environmental requirements like reduction of carbon dioxide emissions require improvement in fuel economy and enhancement of electric machines for driven vehicles of all kinds. Electrical machinery and its use as power source or additional power source in a motor vehicle for electric or hybrid vehicles are commonly known.
Known vehicles with an electric drive comprise an electric engine with an a rotating rotor, e.g., an interior permanent magnet synchronous motor or a rotating electric engine having the rotor mounted thereon, and a vehicle drive apparatus. Typically, a rotor of an electric engine comprises a rotor carrier with a cylindrical support structure for receiving magnetic-flux creating and magnetic-flux leading components.
There are electric machines capable of different operation modes, one for producing torque or driving power for driving a vehicle, in a driving mode, and one to convert kinetic energy of the vehicle into electric energy, in a conversion mode. In a driving mode, such a rotor generates by magnetic interaction with the stator of the electric engine driving power or braking torque in order to accelerate or retard the vehicle. In a conversion mode, the rotor is rotated by the motion of the vehicle and produces by magnetic interaction with the stator of the electric engine electric energy for feeding it into a vehicle power supply.
In both operation modes, the torque generated by the rotor or applied to the rotor must be absorbed from the supporting structure and bearings carrying the rotor which requires a structural configuration capable of dealing with the mechanical load, in particular when load changes occur by changing between the operation modes.
In the automotive sector, there is a large number of ongoing electric and hybrid vehicle developments. Common approaches include at least one to four powerful electric motors in the range of a few kW up to 200 kW to provide driving power to the vehicle. Such engines are safety-critical, since they directly affect the driving of the vehicle. Accordingly, diagnostic systems for the motor are desirable. Yet, there does not exist any particular diagnostic system for the rotor of an electric engine or motor.
The rotor of an electric engine or motor may encounter various errors or failure situations, for example, fracture of the bars in an asynchronous induction motor or additional power losses in the metal components, which may result in a demagnetization of magnets within magnetic-flux creating components and/or magnetic-flux leading components of the motor.